Share This Story!

Explaining blue-green algal blooms, growth of red tide

The bottom line is red tide is indeed a naturally occurring phenomenon that existed long before Europeans came to Florida, and the type of intense bloom we are experiencing now is not normal but is also not unprecedented.

Posted!

Join the Conversation

Comments

Welcome to our new and improved comments, which are for subscribers only.
This is a test to see whether we can improve the experience for you.
You do not need a Facebook profile to participate.

You will need to register before adding a comment.
Typed comments will be lost if you are not logged in.

Please be polite.
It's OK to disagree with someone's ideas, but personal attacks, insults, threats, hate speech, advocating violence and other violations can result in a ban.
If you see comments in violation of our community guidelines, please report them.

OPINION

Explaining blue-green algal blooms, growth of red tide

Michael Crosby
Published 9:23 a.m. ET Aug. 17, 2018

Michael P. Crosby is president and CEO of Mote Marine Laboratory & Aquarium in Sarasota.(Photo: File)

The fact that Southwest Florida is currently experiencing devastating impacts from harmful algal blooms (HABs) is well understood by all of us who call this region home.

What is not as well understood is we are experiencing two simultaneous but separate types of blooms, both with their own harmful impacts to our environment, quality of life and economy.

The ongoing blue-green algal bloom occurs primarily in fresh waters, and can be directly linked to federally directed outflows from Lake Okeechobee, down the Caloosahatchee River into Charlotte Harbor.

The Florida Department of Environmental Protection (DEP) serves as the government lead for dealing with these blooms, while the Florida Fish and Wildlife Conservation Commission (FWC) serves as lead for dealing with red tide blooms. The ongoing red tide bloom is a naturally occurring cyclic event that is not initiated by outflows from Lake Okeechobee, nor inputs from the Caloosahatchee. Red tide begins far offshore in the Gulf of Mexico. As often happens when the winds and currents move together towards the coast, our local coastal communities, beaches and embayments experience the harmful impacts these blooms can have.

Both types of algal blooms must have nutrients to survive and grow. The nutrients both algal blooms utilize come from both naturally occurring sources and from human activities. However, the specific types and combinations of diverse nutrient complexes that each algal species utilize are different.

It is reasonable to hypothesize that the ongoing freshwater blue-green algal bloom is utilizing many of the nutrients coming from Lake Okeechobee and the Caloosahatchee before they get out to the marine waters. Excess nutrients are bad for these freshwater systems, as well as the Charlotte Harbor estuary, no matter how they affect red tides in the ocean, and they should be reduced — whether their source is from lake outflows, storm water runoff from land or through other means. The red tide bloom is being fueled by a complex mixture of nutrients in marine waters from offshore to the coast, and many of these are from diverse coastal sources including non-point-source runoff and inputs from numerous creeks and rivers in the region that carry terrestrial nutrient runoff from rainfall. Though freshwater blue-green algae blooms are generally not expected to thrive in the saltwater environments suitable for red tide, more research is needed on the transport and decay of freshwater blue-green algae out into coastal saltwater, including whether they can provide nutrients or otherwise influence red tide blooms that have reached the coast. In general, much more research is needed to explore the potential linkages among freshwater algal blooms, nuisance algal blooms that can form in the estuary, and ocean-dwelling red tide that forms offshore.

The bottom line is red tide is indeed a naturally occurring phenomenon that existed long before Europeans came to Florida, and the type of intense bloom we are experiencing now is not normal but is also not unprecedented. It is also clear that excess land-based nutrients flowing into Florida estuaries and coastal waters in storm water runoff, rivers and creeks exacerbate the growth of HABs, and that duration of red tide events are correlated with the combination of all riverine flows, not a single river such as the Caloosahatchee.

Years of cutting edge research have significantly increased our understanding of HAB dynamics. Mote Marine Laboratory, a unique Florida-grown and completely independent, nonprofit, global marine research enterprise, has laid out a vision for much more that needs to be done through the creation of an independent Florida-based Marine and Freshwater HAB Center that will utilize innovative approaches and technologies to strategically address: rapid assessment and modeling for HAB forecasting; HAB prevention, control and mitigation of impacts, public health protection and expansion of local community outreach and engagement (access Mote’s red tide resources at mote.org/redtidefaq).

As we see the impacts of these blooms, we are all sharing a blend of emotions including sadness, resolve, anger, desperation and hope for the future. An unfortunate part of human nature is to sometimes feel the need to point a narrow finger of blame and believe that if only we were able to change one thing, the problem will go away.

The causative reason for red tide is just not that simple, and when the facts of science do not implicate a single simple cause of a bloom, it is counterproductive, at best, for any group - left, right or center - to malign results from decades of objective scientific research. Perhaps it’s time to tone down political and emotional rhetoric, and all work together to support innovative research and technology development to actually mitigate the impacts of red tide and get our marine and coastal ecosystems back in balance.

Michael P. Crosby is president and CEO of Mote Marine Laboratory & Aquarium in Sarasota.